Polymerization of olefins using a silicaphosphoric acid catalyst

ABSTRACT

The polymerization, especially the oligomerization, of olefins, for example, propylene and/or butene, wherein the improvement resides in the use of a solid catalyst consisting essentially of a silica carrier and phosphoric acid, the molar ratio of P2O5 to SiO2 being between 0.6 and 0.95, and the content of the crystalline C form of silicium phosphate being between 75 and 95 percent, said catalyst having been produced by heating a mixture of silica with phosphoric acid at 550 to 1,000*C, and then in a second step, contacting the resultant heated catalyst with steam at 100*-300*C so as to activate same.

United States Patent [1 1 .lugnin et al.

[ Sept. 11, 1973 1 1 POLYMERIZATION OF OLEFINS USING A SILICA-PHOSPHORICACID CATALYST [75] Inventors: Bernard Juguin; Jean Francois Le Page,both of Rueil Malmaison, France [73] Assignee: lnstitut Francais duPetrole des Carburants et Lubrifiants, Rueil-Malmaison, France [22]Filed: Jan. 11, 1972 [21] Appl. No.: 217,046

Related US. Application Data [62] Division of Ser. No. 869,860, Oct. 27,1969, Pat. No.

[30] Foreign Application Priority Data Oct. 31, 1968 France 68172358[56] References Cited UNITED STATES PATENTS 3,201,486 8/1965 Bielawskiet al. 260/671 R 2,860,173 11/1958 Jones et a1. 260/671 C 3,183,2335/1965 Bloch 260/671 R 3,673,111 6/1972 Hovarth et al. 252/435 2,613,18710/1952 Mavity 260/683.15 2,575,457 11/1951 Mavity 260/683.15 2,694,68611/1954 Reeves et a1 260/683.15 3,112,350 11/1963 Bielawski et a1...260/683.l5 3,586,729 6/1971 Juguin et a1. 1 260/683.l5 3,651,168 3/1972Stoessel et a1. 260/683.l5

Primary ExaminerPaul M. Coughlan, Jr. Attorney1. William Millen 5 7ABSTRACT The polymerization, especially the oligomerization, of olefins,for example, propylene and/or butene, wherein the improvement resides inthe use of a solid catalyst consisting essentially of a silica carrierand phosphoric acid, the molar ratio of P 0 to SiO being between 0.6 and0.95, and the content of the crystalline C form of silicium phosphatebeing between 75 and 95 percent, said catalyst having been produced byheating a mixture of silica with phosphoric acid at 550 to l,OO0C, andthen in a second step, contacting theresultant heated catalyst withsteam at l00-300C so as to activatesame.

7 Claims, No Drawings POLYMERIZATION F OLEFINS USING .ASlLICA-PHOSPHORIC ACID CATALYST This is a continuation, division, ofapplication Ser. No. 869,860, filed Oct. 27, 1969 now Pat. 3,657,150,patented Apr. 18, 1972.

This invention relates to a process for manufacturing a solid catalystconsisting of a silica-containing carrier and phosphoric acid, andcontaining a total of 60 to 70 percent by weight of phosphoric acid,expressed as P 0 corresponding to molar ratios of P 0 to SiO, between0.6 and 0.95, said process comprising, in a first step, heating up amixture of silica with phosphoric acid, preferably a polyphosphoricacid, to a temperature between 550 and 1,000C, preferably between 650and 850C, said mixture containing at least 60 percent by weight, andpreferably 60 to 75 percent by weight, of phosphoric or polyphosphoricacid, thus resulting in a composition having a molar ratio of P,0,, toSiO between 0.6 and 0.95, and thereafter, in a second step, contactingthis composition with steam, either pure or diluted with a gas, at atemperature of 100 to 350C, preferably 150 to 250C.

During the heating step, losses of 150,, often occur; it is thuspreferred thatin the starting mixture of silica with phosphoric acid(before heatinghthe molar ratio of P 0 to S be5 to 10 percent higherthan the desired final ratio.

Many catalysts of the solid phosphoric acid type have been disclosedheretofore, and several of them are industrially available.

The prior art is disclosed, for example, in US Pat. No.

3,112,350. According to this patent, it was known to manufacturecatalysts by heating mixtures of phosphoric acid with asilica-containing carrier at temperatures lower than 425C except whenthe heated mixture was further contacted with steam, in which case, themaximum heating temperature is from 455C to 510C, the resultingcomposition being thereafter reacted with steam at about 230-290C. Theabove patent discloses substituting the thus defined catalysts of lowactivity and poor mechanical strength, with catalysts obtainedv byheating at a higher temperature (550 to 900C) mixtures of higherphosphoric acidcontent, the molar ratio of P 0 to SiO, being thenhigherthan I. These catalysts are directly used for treating olefinicfeedstocks., Y 5 According to the present invention, the catalyst ismade from silica of a purity preferably higher than 94 percent andisjsubjected not only to a heating at high temperature (550 to 1,000Cand preferably 650to 850C) but also to a further treatment with steam,the molar ratio of 1?,0, to S10, being lower than 1.

According to a preferred embodiment, the catalyst is heated in the abovetemperature range for a time sufficient to decrease the P,O, contentextractable in one hour with water at 20C down to a value lower than 15percent but higher than 2 percent, by weight, this content beingdetermined with the powderedcatalyst (at least 90 percent of theparticles being lower in size than 100 microns); thereafter the catalystis activated with steamso as to obtain a P,O, content extractable underthe'above conditions of 1.5 to 15 times, and preferably two to fourtimes,the content after heating, this content remaining less than 30percent by weight'in any case. As a result, there is obtained afinalcatalyst containing a mixture of silicium phosphates of thecrystalline types B, C and D, with a higherproportion, e;g.,

75-95 percent of the C phase. These crystalline types may be determinedeasily by the X-ray diffraction method, for example according to Boulleand .lary in Comptes-rendus de 1 Academic des Sciences, July 15, 1953,or to US Pat. No. 3,201,486.1n the latter patent, it is shown that thebest catalysts contain about 60 to 90 percent of the crystalline C phaseand are obtained only with molar ratios of P 0 to SiO, higher than 1,preferably between 1 and 1.5. In fact, catalysts which areso rich in P 0cannot be manufactured easily since their mechanical properties afterheating are usually poor.

According to this invention, catalysts may be manu-v 'after heated inthe. range of 550 to 1,000C, preferably 650 to 850C. After heating, themajor crystalline type is D; it is very difficult to obtain thecrystalline phase Cby mereheating, since at these high temperatures andwith molar ratios of P 0 to SiO, lower than 1, it is quickly convertedto the D phase, the la'tter giving catalysts of low activity. Theprocessof this invention makes it possible for the. D phase to revert to'thephase C, by means of a re-activation treatment with steam, attemperatures of about 100 to 350C, preferably 150 to 250C.

- Asa rule, the higher theheating temperature, the longer istheactivation treatment or the higher'the steam pressure. The higherheating temperatures will be associated with the higher P 0 contents.Finally, the higher-temperatures will'be employed with silicas of lowerpurity. 1

The preferred carriers contain in the dry state, from 94 to 99.5 percentby'weight of SiO, andinclude synthetic porous silica, or natural silicasuch as diatomaceous earth aftera treatmentwhich reduces the'content ofimpurities (Na,0, K,O, CaO, MgO, Fe,0,and the like) below 6 percent byweight. Aluminum silicates, although not excluded, are less desirable.However the best results have been'obtained' with silica carriers havinga $10, contejntbetween'96 and v99 percent. With contents lower than 96percent, the catalyst has tobe heated up totemperatures higher' than850C, whichresults in very long reactivation periods which are expensiveand increase the final cost of the catalyst; with contents higher than99 percent, the catalyst exhibits poor mechanical properties. tTheactivation step may follow the heating-step immediately or maybecarried out later, for example-in good results may also be obtainedbeyond these limits.

As to the choice of the phosphoric acid and the already known steps ofthe process, attention is invited to the above-mentioned US patents. Asdescribed in these patents, the bestcatalysts will be obtained fromphosphoric acid containing about 79 to 90 percent by weight of P knownas polyphosphoric acid.

The carrier is admixed with phosphoric acid at a preferred temperatureof to 300C, particularly. between 90 an 180C.

The heating time is preferably 0.5 to 30 hours, these values being notcritical.

Although the catalysts according to this invention may be used for alltypes of polymerizations of monoor poly-olefins mentioned in theabove-stated U.S. patents, and also for alkylation reactions, it hasbeen found that they exhibited a particularly high selectivity in thefollowing condensation reactions: manufacture of heptenes byco-polymerization of propylene with butenes, manufacture of iso-octenesby dimerization of butenes, manufacture of gasoline by condensation offeedstocks having a high content of propylene and/or butenes,trimerization of propylene to manufacture bases for detergents,production of cumene by alkylating benzene with propylene.

The operating conditions are known per se; water is preferably used, inan amount of 50 to 3,000 parts per million of parts by weight,preferably 150 to 800 parts per million. The temperatures are usuallybetween 100 and 300C.

The following, non-limitative examples are illustrative of thisinvention:

EXAMPLE 1 Silica extrudates having a SiO content of 98 percent and apore volume of 105 ccm per 100 grams are subjected to impregnation witha solution of polyphosphoricacid at 140C, the impregnation time being 2hours. After impregnation, the resulting composition is dried.

After drying, a first portion is heated up for 2 hours at 300C in anoven. This constitutes catalyst A.

Another portion is heated at 500C for 2 hours and constitutes catalystB.

Still another portion is heated at 750C for 2 hours and forms catalystC.

A portion of catalyst C has been re-activated at 150 to 250C underatmospheric pressure for 4 hours by means of a mixture of air withsteam, eachused in an amount of 50 liters per hour per 100 grams ofcatalyst: this constitutes catalyst D which is one object of thisinvention. 1

After manufacture, the total amount of P 0 by weight and the amount of P0 extractable in 1 hour with water at 20C were determined according tothe method of Van Wazer, Griffith and Mc Cullough, Analytical Chemistry,vol. 26, No. 11, November 1954. The results are summarized in table I.

These four catalysts were also analyzed by the X-ray diffraction methodso as to determine the crystalline types; the results are also given inTable l.

TAB LE I 1 With reactivation.

These 4 catalysts were used for polymerizing an olefinic feedstock C andC in view of producing heptenes. The latter are starting materials formanufacturing plasticizers of the octyl phthalate type. The compositionby weight of the olefinic feestock was as follows:

Saturated hydrocarbons (C -,+C,) 2.5 percent Propylene 34.0 percentl-butene Z-butenes 32.2 percent iso-butene 30.5 percent 1,3-butadiene0.6 percent iso-pentane 0.1 percent water 200 parts per million Theoperating conditions as well as the results are summarized in Table II,the pressure was bars.

TABLE II Operating conditions Conversion Selec- Reactlon Feeding ratetivit-y temperrate per run to hepature C. (V.V.H.) percent tenesCatalyst A 250 6 81 24 B 250 5 i 80 35 C 250 2 58 43 D 250 4 79 51.5

V.V.H. is the hourly volume of liquid feed charge per volume ofcatalyst.

the conversion rate per run is given with respect to the startingolefins V 7 the analysis of the product is made by mass spectrometryThis table shows the high activity of catalyst D according to thisinvention.

Catalysts A and B are very active, although not selective, since their P0 content extractable in one hour with water at 20C is too high and thecrystalline type B predominates. Conversely, catalyst C has a lowactivity since the proportion of the D phase is high, and the P 0content extractable with water at 20C is too low.

It is thus preferred that the P 0 content extractable with water at 20Cbe in the range of 15 to 20 percent, in order to obtain a mixture ofsilicium phosphate in which the crystalline type C predominates (morethan percent).

EXAMPLE ll Catalysts A, and D of example I are used for polymerizing anolefinic C cut in view of producing isooc- Temperature 250C Pressure 70bars Rate of liquid feed charge (V.V.H.): 4 The results are summarizedin Table III.

TABLE III Conver- Selecsiou tivity Cs isomers rate to isoper run octcnesTrimothyl Dimethyl Methyl percent percent pentones hexenes hupteuesCatalyst A 83 64 70 23 7 l3 81 78 83 13 4 D 78 95 98 2 Here again,catalyst D of this invention gives superior results. The selectivity toiso-octenes is very high and, above all, among the various ethylenicisomers of the C type, there are 98 percent of trimethylpentenes; it iswell-known that, among the C isomers, the latter are those for which theoctane rating changes the least 15 after hydrogenation. Thus thiscatalyst is quite convenient for producing gasoline of high octanenumber.

EXAMPLE III isobutane 15 percent isopcntane 0.1 percent water 200 partsper million. The operating conditions are those of Example II. Theresults are given in Table IV.

TABLE IV- Conversion Distillation rate per run Octane number numberA.S.T.M. with res act to RESEARCH (Pressure: initial 0 efins the CLEAR761 mm H percent 80 percent 94 percent 97 percent 99 percent 101 78 100percent 103 percent 107 percent 111 percent 122 percent 147 percent 178final point 196 residue 0.8 I: loss 0.7

This shows the high quality of the gasoline obtained according to thisinvention.

The Research clear octane number is very high and from the ASTMdistillation point of view,

will be no need for any additional distillation column (rerun column) tocut this gasoline at 200C, when the colour specifications are met.

A portion of the obtained gasoline has been hydroge- Y can'tly higher.

EXAMPLE 1V Catalysts A, B and D of example I have been used forpolymerizing propylene in order to produce propylene trimers.

. The operating conditions were as follows:

temperature 200C 1 pressure 70 bars liquid feed rate (V.V.H.): 3

The results are given in Table V TABLE V Catalyst TATR conversionSelectivity to I rate of propylene trimers A 85 53 B 83 64 D 80 81 Hereagain, the results show the higher quality of the catalyst of thisinvention. For about the same conversion rates per run, the selectivityto trimers is signifi- EXAMPLE v Catalysts A, B and D of example I areused for producing cumene'by alkylating benzene with propylene.

The operating conditons are as follows:

temperature: 250C pressure: 50 bars feed rate: 2 volumes of benzene pervolume of catalyst and per hour.

molar ratio of benzene to propylene 6 The results are given in Table VI.Here again the catalyst of this invention gives better results.

TABLE VI Catalyst Conversion rate Yield of cumene with respect ofpropylene to consumed benzene ment wherein said catalyst consistsessentially of a silica carrier and phosphoric acid, the molar ratio ofP 0,

to SiO, being between 0.6 and 0.95, and the content of the-crystalline Cform ofthe silicium phosphate being between 75 and 95 percent, saidcatalyst being prepared by a process comprising in afirst step, heatingat 550 to 1,000C a mixture of silica with phosphoric acid, saidmixturecontaining at least 60 percent by weight of phosphoricacid,therebyobtaininga composition in which the molar ratio of to SiO, isbetween 06 and 0.95, and in a second step, contacting at' l00 -300C thepreviously heated catalyst with steam nated in the presence of acatalyst containing nickel on I silica; after complete hydrogenationtheResearch clear octane-number was 99.

SO 85 t0 activate same.

2. A processasdefined by claim 1 wherein said olefin ispropylene.

3; A process as defined by claim 1 wherein said olefin is a butene. 4. Aprocess as defined by claim 1 wherein 6. A process as defined by claim 1wh r i said l 7. A process as defined by claim 1 wherein saidpolymerization is dimerization. merization is trimerization.

2. A process as defined by claim 1 wherein said olefin is propylene. 3.A process as defined by claim 1 wherein said olefin is a butene.
 4. Aprocess as defined by claim 1 wherein said olefin is a mixture ofpropylene and butene.
 5. A process as defined by claim 1 wherein saidpolymerization comprises the copolymerization of propylene with butene.6. A process as defined by claim 1 wherein said polymerization isdimerization.
 7. A process as defined by claim 1 wherein saidpolymerization is trimerization.